Cooling device



Aug. 28, 1951 c. E. DAwLl-:Y ET A1.

COOLING DEVICE Filed Sept. 17,. 1948 7'0 EAV/H067" PUMPS VCl/UM 7 rp M rn man i@ WFTNESSES:

Patented Aug. 28, 1951 COGLING DEVICE Clarence E. Dawley and John .E. Schiveree, Bloomfield, N. J., `assignors to Westinghouse Electric Corporation, ,East Pittsburgh, Pa., a corporation of rPennsylvania AApplication September 17, 1948, Serial No. 49,768

'-3 Claims. (Cl. 62--91.'5)

This invention relates to a cooling .device as an Yimprovement in the Dewar .flask trap which .is used as a combination refrigerant-holding bottle and .trap .in connection with a mass .spectrometer.

The principal object of our invention, .generally considered, is to .provide a cooling device for use in `connection with an evacuating system for condensing vapor, such as that of mercury, and preventing it from traveling rfurther into the system, .as from a mercury pump.

Another object of our invention :is to provide a Dewar flask with tubulations, one ,at a side and one at the bottom, andone more outer walladded, silvered, and the enclosure providedby said youter wall evacuated in order to economize on the use of refrigerant.

A further object of our invention is to provide, in a device of the character described, a glass spiral in the lower tubulation between the outside wall and the Vbottom of the Dewar flask, to relieve strains caused by unequal expansions and contractions.

Other 'objects and advantages of the invention, relating to the particular arrangement fand construction of various parts, will become 'apparent as the description proceeds.

vIn the drawing, the single figure is a longitudinal sectional view of a cooling device 'embodying our invention, shown approximately to scale and about one third size.

The cooling device embodying our invention, one embodiment of which is illustrated in the drawing and designated II, is an improvement over that which has been used in connection With a mass spectrometer, for the condensation of mercury vapor froma mercury pump used for evacuating purposes, or the freezing down of any condensible vapor which may be present in the high vacuum side of the system, to thereby prevent the same from traveling further in the vacuum system. Due to the compact design of the equipment, some parts had to be made special in order to t into the limited space. These parts included the cold trap, which in the equipment referred to was designed to use liquid air as the refrigerant.

In order to keep the high speed pumping, and also to fit into the space available, a doublewalled receptacle, in the nature of a Dewar flask, was used, but tubulated at the side and bottom, and not permanently evacuated. The receptacle or flask employed consisted of, as shown in the drawing, an inner generally hollow cylindrical container or bottle I2, with a generally hemispherical `closed bottom portion, for holding refrigerant I3, such as liquid air or Dry Ice. Enclosing said inner wall was a correspondingly shaped outer wall, designated I4, spaced .therefrom, connected thereto at the upper edge of the inner wall, and forming a refrigerating enclosure I5 through which uid may pass, a side tubulation .IB and a bottom tubulation vI.'I being providedon the wall 'I 4.

Such an arrangement used the space between the walls as the vacuum insulation, vacuum system itself, and also as a condensing chamber, permitting the bottle to .be .iilled from the top Without having to move .'it in the limited space. A vacuum .cover I8 of conforming `shape was provided for said bottle, asfillustrated, the vinner surface being silvered. The tubulation IIB vconnects with the vessel to be evacuated, while the tubulation I'I extends to 'the exhaust pumps. Any mercury vapor -or the like from said pumps is condensed on the flask I2 and drops back into the tubulation fII.

The Vdisadvantages kof the original design are that the outer surface of the refrigerant-containing portion I2, and the inner surface of vthe spaced wall .I4 if silvered would 'become amalgamated vby the mercury and its eiiciency considerably decreased. Without silvering, the bottle is very wasteful .in the use of refrigerant. VThe use of Dry Ice, instead of liquid air, in order to economize, involves considerable expense in connection with such use, as will be noted from the following statistics.

At present such a device must be filled with Dry Ice at least once every eight hours, and considerably more often if liquid air is used. It has been necessary to secure approximately fifty pounds of Dry Ice every twenty four hours, for supplying such a device, requiring attention during nights, week-ends and holidays when the equipment is in continuous operation, which is the case in most installations.

In accordance with our invention, we have improved on such design by adding one more wall, as an outside wall I9, of a size and shape corresponding with the outer wall 0I" the Dewar flask and with its upper edge connected to the upper edge of the intermediate wall I4 extended beyond the top of the inner Wall I2, and forming a curved seat for the cover I8. The length of this outer wall I9 was increased over the length of the original modified Dewar ask to include the glass spiral illustrated, so that it is about 19 inches in the embodiment under consideration. The inner surface of the outside wall I9 is 3 silvered, or coated with specular material, desirably metal, suitable for efciently reflecting radiant energy, especially heat, as well as the outer surface of the spaced wall I4, the space 20 between said walls being evacuated. The distance at the side between the outer wall I9 and the spaced wall I4 being very small in the illustrated embodiment, the tubulation I6 may go straight therethrough, as illustrated. But the tubulation Il desirably continues between the bottom of the spaced wall I4 and the bottom of outside wall I9 as a helix or spiral to its point of connection with the bottom of the outside wallv I9, from whence it may extend without spiral ing to the exhaust pumps. This curvature to helical form relieves thermal strains due to the difference in operating temperatures between the middle and outer walls, which are sealed together by ring seals. The outer cylindrical wall of the' bottle has to conform to shape and diameter of existing equipment, which required a decrease in the diameter of the inner container I2, thereby decreasing its volume.

In spite of the smaller volume, we have found that such an improved bottle, as illustrated in the drawing, will operate four days with onelling consisting of three pounds of Dry Ice. We have therefore decreased the consumption from about fifty pounds per day to about six pounds per week, and eliminated the necessity of attention during periods when the operator is not with the equipment.

Although a preferred embodiment of our invention has been disclosed, it will be understood that modifications may be made within the spirit and scope of the appended claims.

We claim:

1. A cold trap comprising a double-walledA receptacle in the nature of a Dewar flask, an evacuated cover therefor, a wall outside of and spaced from the outer wall, and to which the upper edge of said flask is connected to form an enclosure therebetween, a tubulation extending from a side of the outer wall of, and communieating with the space between the walls of, said flask and connected to and passing through said outside wall, another tubulation passing through the bottom of said outside wall and also communicating with the space between the walls of said 1 '4 flask, and the enclosure formed between the outer wall of said flask, its tubulations, and said outside wall, being evacuated.

2. A combination refrigerant bottle and cold trap comprising a flask for holding refrigerant, an evacuated cover therefore, a wall spaced from the outer surface of said ask and forming a refrigeration enclosure through which iiuid may pass, an outside wall spaced from said first-mentioned wall and forming an evacuated enclosure therewith and a tubulation passing through a side of said outside Wall and communicating with said refrigeration enclosure, and another tubulation passing through the bottom of said outside wall and also communicating with said refrigeration enclosure.

3. A combined refrigerant bottle and cold trap comprising a flask for holding refrigerant, an evacuated cover for said ilask, a wall spaced from the outer surface of said liask and forming a refrigeration enclosure through which iiuid may pass, an outside wall spaced from said rstmentioned wall and forming an evacuated enclosure therewith, the inner surface of said outside wall and the outer surface of said spaced wall being silvered, a tubulation passing through a side of said outside wall and communicating with said refrigeration enclosure, and another tubulation passing through the bottom of said outside wall and also communicating with said refrigeration enclosure, a part of said tubulation between the bottom of said refrigeration enclosure and the point of union with said outside wall being helically curved to relieve strains caused by thermal changes.

CLARENCE E. DAWLEY. JOHN E. SCHIVEREE.

REFERENCES CITED The following references are of record in the iile *of this patent:

UNITED STATES PATENTS Number Name Date 1,088,194 Whitton Feb. 24, 1914 1,307,999 Buckley June 24, 1919 2,370,703 Zaikowsky Mar. 6, 1945 2,465,229 Hipple Mar. 22, 1949 2,512,040 Slobod June 20, 1950 

